The original Xbox gaming console launched on November 15. It went on to make an undeniable mark on video game history by introducing a third party into a console race that was largely dominated by PlayStation and Nintendo systems. Xbox, and especially its successor, the Xbox 360 took the video game industry by storm by emphasizing online play, growing the Xbox Live service, and bringing beloved franchises such as Halo, Gears of War (which is also celebrating its 10-year anniversary) and many others.

Xbox celebrated its 15-year anniversary yesterday, with players having spent over 100 billion collective hours gaming, unlocking over 32 billion Achievements, and finding more the 4 billion friendships. Microsoft encouraged fans to post their favorite memories on social media using the hashtag #15YearsOfXbox, which has led to a huge number of well-wishers and waves of nostalgia. The Xbox team also spent the day playing both alongside and against its community across a variety of games, some of which were livestreamed so that those that couldn’t participate could still watch. All this, of course, was accompanied by giveaways featuring special content for games such as Forza Horizon 3 and Halo 5: Guardians.

This year is rather exceptional for its anniversaries. The PlayStation Store began celebrating its 10-year anniversary last week with (what else?) a huge sale, which is currently in its second round. Blizzard had three reasons to party hard the week before, given how it was the 25th anniversary of the company, its 10th BlizzCon, and the 20th anniversary of its immensely popular Diablo series. That’s a lot of celebrating, and 2016 has plenty of marketing opportunities to take advantage of nostalgia to promote new games and hardware.

For example, PlayStation went all out in celebrating its 20th anniversary by not only hosting a massive sale last year, but also by announcing the PlayStation 4 20th Anniversary Edition on December 3, 2014, marking 20 years from when the first PlayStation console launched in Japan. Only 12,300 of the gray (matching the original color of the PlayStation) PS4 were made, which included a matching controller and PlayStation Camera. Sony also made a special 20th anniversary playlist via PlayStation Music on Spotify. Meanwhile, fans in the UK could pick up a special limited-edition SteelBook patterned after the original PlayStation, containing a £20 Wallet for the PlayStation Store and a 12-month PlayStation Plus membership.

Getting back to 2016, a number of exceptional game franchises reached major milestone years. The Civilization series celebrated 25 years of rewriting history with a special collector’s edition of the recently released Civilization VI, which includes a hardcover art book and a commemorative coin set. Sonic the Hedgehog celebrated 25 years in July by throwing a big party for San Diego Comic-Con attendees and announcing Sonic Mania for next year. Bethesda and id Software announced Quake Champions at E3 earlier this year, marking two decades for one of the first game franchises that regarded first-person shooters as a kind of sport. The Dead Rising series celebrated its 10th anniversary by releasing a remastered version of its first game for current consoles and PC, paving the way for the launch of Dead Rising 4 in December. The new game features Frank West, the original protagonist of the series, giving fans all the more reason to jump into the zombie stomp.

Tomb Raider went the extra mile in celebrating 20 years of adventuring with Lara Croft with a multitude of events and releases, including a specially composed music collection, an art book, and the Rise of the Tomb Raider 20th Anniversary Edition, which supports high-end hardware such as the PlayStation Pro and PlayStation VR.

Nintendo celebrated 30 years of The Legend of Zelda by revealing a set of special Amiibo figures in addition to a deluxe, limited edition 2-disc music CD collection in Japan called The 30th Anniversary The Legend of Zelda Game Music Collection. That’s in addition to dedicating a giant E3 booth to promoting the franchise’s newest entry, The Legend of Zelda: Breath of the Wild, which launches next year for the Wii U and Nintendo Switch. This year also saw the 20th anniversary of Pokémon, which was celebrated in a myriad of ways, including a Super Bowl commercial and a special web page where fans look through the franchise’s history among other activities. However, the immense success of Pokémon GO and the newly released Pokémon Sun and Moon are reason enough to celebrate by themselves.

Resident Evil has been celebrating its 20th anniversary for the better part of the year and perhaps longer with remastered versions of previous games releasing for current-generation consoles, the launch of a new game, Umbrella Corps and releasing a T-Virus perfume in Japan. All the celebrating is building up to the launch of Resident Evil 7 in January, which will be one of the first full-length games to include PlayStation VR support from start to finish.

Gamers have a tremendous opportunity to support their favorite franchises, while brands can take this opportune time to join in the festivity with promotions and products that help celebrate decades of video game history. And it’s not too early to start planning for next year, as Final Fantasy’s 30th birthday will take place on December 18, 2017. Square Enix opened its official Final Fantasy anniversary portal website in Japan last September, which currently doesn’t have much, but building anticipation is something that the role-playing series has grown quite adept at.